U.S. Climate Bill Part of Solution but Not the Whole Solution

Bill Chameides
Dean, Duke University's Nicholas School of the Environment

Co-written by Bill Chameides and Prasad Kasibhatla

The climate deniers have a new argument: don't pass climate legislation because it doesn't cut emissions enough.

That's right. It's not that the globe is not warming, or that the warming is not caused by human activities, or even that passing climate legislation would cost too much. Now it's the Waxman-Markey American Clean Energy and Security Act of 2009 (H.R 2454) is no good because it does not slow global warming enough. It's brilliant, don't you think? How can anyone who favors climate legislation support a bill like that?

Setting the Stage

Following the same basic approach taken by Chip Knappenberger (and spreadthrough the blogosphere), we'll compare what would happen if Waxman-Markey were passed with what would happen in the absence of the bill -- we call this latter scenario "business as usual," or BAU for short.

We start with the BAU emissions scenario from the U.S. Energy Information Agency [xls], which goes out to 2030, then to 2050, assuming a continuous rate of growth, and then assume constant emissions from 2050 out to the end of the century. (See graph.)

Waxman-Markey and U.S. Emissions

We then compare these BAU emissions with what would happen under a Waxman-Markey scenario, which calls for an 83 percent emissions reduction below 2005 levels by 2050.

Under the BAU scenario the United States would emit about 280 billion tons of carbon dioxide (CO2) between now and 2050, and about 680 billion tons of CO2 between now and 2100.

Under Waxman-Markey on the other hand, the emissions would be 140 and 190 billion tons of CO2 by 2050 and 2100, respectively. So the U.S. adoption of Waxman-Markey would prevent the emission of:

about 140 billion tons of CO2 by 2050 and

490 billion tons of CO2 by 2100.

Warming Prevented Under Waxman-Markey

A recent paper in Nature by H. Damon Matthews of Concordia University and colleagues provides a useful metric for converting CO2 emissions into temperature changes. They estimate that for every billion tons of CO2 emissions, global temperatures increase by about 0.0004 degrees Celsius. Factoring that metric in, we get that Waxman-Markey's adoption would decrease the net global warming by about:

0.06 Celsius by 2050 and

0.2 Celsius by 2100.

Gosh, at this point you might be thinking, all that hoopla over Waxman-Markey and all we get is a measly tenth of a degree or two drop? Maybe it's not worth it.

And if you're thinking that, you'd be wrong. You've fallen for the bait. You just can't look at this problem a single country at a time. To illustrate, consider doing the same experiment for China.

The Chinese Experiment

Let's compare BAU emissions from China with the lower emissions the Chinese would have have if they adopted a Waxman-Markey type of emission reduction.

In this case, a Waxman-Markey framework for China prevents Chinese emissions in the amount of:

350 billion tons of CO2 by 2050 and

1,160 billion tons of CO2 by 2100.

Using the Matthews et al. metric, that comes out to an avoided warming of approximately:

0.15 Celsius by 2050 and

0.46 Celsius by 2100.

These are larger temperature differences than those projected for the United States following the Waxman-Markey bill but by themselves not nearly large enough to avoid dangerous anthropogenic interference with the climate.

Imagine ... Climate Debate in the Chinese Politburo

So with these numbers in mind, imagine a climate discussion in the Chinese Politburo. There is a proposal for a Wang-Hue Climate Stabilization Decree to cut Chinese emissions by 85 percent by 2050. But the decree is opposed by some because it will only reduce global temperatures by a measly 0.15 degree Celsius by 2050. "Too small," they say. "Not worth doing."

Many rise to argue against the naysayers in our fictional Chinese Politburo, but then the assembly is hushed as the renowned statesman and climate denier Comrade Yung-Inhofe Xing takes the floor and goes one better than any U.S. naysayer could.

"Since the beginning of the Industrial Revolution," the Comrade explains, "about 1,200 billion tons of CO2 have been emitted into the atmosphere from the burning of fossil fuels and a little less than 30 percent or 360 billion tons of all of those emissions have come from the United States. (Source) That's more than any other country and roughly equivalent to a warming of 0.14 degree Celsius. By comparison, China's historical contribution is a mere 80 billion tons or 0.03 degrees Celsius. (Source)

"So my proposal, Comrades," Yung-Inhofe Xing expounds, "is that we Chinese continue to emit CO2 unabated until our contribution to global warming is as large as that of our esteemed friends from the United States of America."

The decree is defeated.

What's Wrong with this Picture?

As long as individual countries focus on their own little contribution, nothing will ever happen. It's sort of like this:

You're at a party with 29 other revelers. The beer just ran out and $30 is needed to get more beer. The hat is passed around for contributions, but each person thinks, "If I put in a dollar all it will add is 1/30th or 3 percent of what is needed. That's a tiny amount, too small to worry about ... I think I'll just pass." And no one adds to the hat, and no beer gets bought.

Global warming is an international problem, requiring international action. No single country can solve the problem on its own, and to focus on the impact of a single country's emissions reductions is misleading, not to mention worrisome. The amount of warming obtained from the U.S. acting alone is small as is the warming from China acting alone. But add them together and you start to get somewhere. Ultimately, it's going to take all the major economies of the world to get traction on this problem.

So the argument that Waxman-Markey doesn't do enough is another of those red herrings. Looks good from a distance, but up close, not so much.

In fact, Waxman-Markey provides a pretty good road map for a global solution. If Waxman-Markey were followed by the other big economies, there would be a significant difference in the climate: a decrease in the net global warming by almost 2 degrees Celsius, likely enough to avoid the most serious consequences of global warming.

In the case of global warming, it doesn't take a village — it takes the world.

Dr. Bill Chameides is the dean of Duke's Nicholas School of the Environment and a member of the National Academy of Sciences. He blogs regularly at theGreenGrok.com.

Prasad Kasibhatla is Associate Professor of Environmental Chemistry and Associate Dean for International Programs at Duke's Nicholas School of the Environment.